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April 9 s. R. MASON PROCESS OF AND APPARATUS FOR CLEANING METAL Filed. June '7, 1923 SumnerRHason Patented Apr, ltd, 3192?.

SUMNER RED'W'AY MASGN, (if? ll' /ILIiZIETTE,

ZLLIIQ'OIS, ASSIGNGR T VTESTEEN ELEG- TRIC COIli IlEANY, INGUREQBATED, OF IQ'LE'W YGBK, LU. COBPORATIQN OF NEW YORK.

OF AND APTFARATUg IEQR CLEANING .METAL.

Application filed .Tune '7,

This invention relates to a process of and apparatus for cleaning metal, and more particularly to a process of and apparatus for cleaning metal parts PlCDzll'fltOl'Y to plating.

In order for a metal surface to be pro crly finished it is necessary that it be first thoroughly cleansed. of all substances which might in any way interfere with the finish inc; thereof. In the case of iron these suhstances frequently take the form of higher iron oxides, such as magnetic and ferric oxides, or foreign impurities such as oil, organic matter, and carbonaceous and graphi'tic substances.

Due to the diversity of character of "these substances it is sometimes necessary to subiect the surface to a plurality of operations in order to insure the props cleaning there-- of. It is desirable that [handling of the surfaces during; the cleaning process be reduced to a minimum to preventthe accumulation thereon of additional impurities.

An object of this invention is to simplify and otherwise improve the process of cleaninn metal surfaces preparatory 'to finishing.

Another object is to improve electrolytes employed in cleaning metal parts.

It is believed that the invention will be fully comprehended from the following do soription and the accompanying drawings, showing apparatus which may be employed in practicing the invention.

In the drawings,

Figs. 1 to t show crosssectional views of the tanks with associated openings, suspension racks, electrolytes, and schematic circuits employed in practicing the invention;

Fig. 5 shows an enlarged elevation of the improved article suspension rack. and

Fig. 6 shows an enlarged fragmentary of Fig. 5. I

Referring to the drawings in detail, an earthenware tank 10 contains an electrolyte 11, consisting preferably of ferric chloride with from 5% to 10% hydrochloric acid. A source of alternating current, for instance, an alternating cl'irrent generator represenh ed generally by 20, is connected so that conductors from opposite terminalsEZl and thereof lead, to alternate bus bars and 31. resting on the tank 10. Racks 50 are hung; on these bus bars in the manner illustrated and may be constructed as shown in Figs. 5

1923. Serial No. 84.3,867.

and 6. In accordance with this structure two uprights 51; of brass, support cross bars 52, also of brass, which are fastened to the uprights by suitable means, for instance, rivets 52-3. Hooks of copper or iron are intimately connected to the cross bar in a. manner to secure a water-tight contact there with, as for instance, by means of bolts 55. A tank 12, which may also be of earthenware, contains water 13. A cross bar is supported by the tank and from it the rac {S are suspended while washing. 60 represents the source of a direct current, as for instance, a direct current generator, whose positive terminal 61 is connected to a bus bar 38 resting on insulators supported by a tank 14-. From this bus bar the rack is suspended. The tank 14, whose inner surface may be a conductor, as for instance, a cast iron tank, is connected to the negative terminal 62 of the aforesaid direct current generator in such a manner that when an electrolyte 15 is prcsentin the tank, the inner surface thereof may act as cathode, while the raclr 50, and parts hun therefrom will act as an anode. It is to be understood, however, that a separate conductor may be placed in the electrolyte as a cathode in stead of using the inner surface of the tank therefor.

[in electrolyte of great efficiency to be used in this step of the process is con'n posed of approximately one part of sulphuric acid having a specific gravity of 1.84 and one part pure water. A greater concentration than this is found to deleteriously affect the part being cleaned, while a lesser retards the process markedly.

[in earthenware tank 16 contains a. solo- :tlOll 17 of hydrochloric acid, and supports view partially in section along; the line Gii a cross bar rhck 50.

in practicing: the invention, the parts 67 to be cleaned are hung upon hooks 54 in the rack 59. lj cinp; secured thereto by wires 68 and are immer ed in a bath of a soluble chloride, prefcr zy a solution of hydrochloric acid and ft. m chloride, and subjected to alternating); curat therein, alternate racks being connec to opposite terminals of the source of this current explained above. By the use of an electrolyte of ferric chloride and hydrochloric acid in this step, in which the hydrochloric acid constitutes approxifrom which is suspended the mately 5% or 10% of the total, the electro lytic action of the alternatii'ig current on this solution liberates hydrogen, and it s believed that the ferric oxide, or the magnetic oxide scale on the iron parts, is reduced thereby to ferrous oxide. The hydrochloric acid 111 the solution then dissolve; the reduced oxide. A straight ferric chloride solution n ithout the hydrochloric acid may be used in place of the above and 1)1efl able to hydrochloric acid alone. By this operation the scale and rust are removed from the part, but the iron itself is not deleteriously affected as the gas formed during the action protects it. After being subjected to this process the racks are removed from the electrolyte, best results being obtained by ren'ioving the center rack first, nu Ring the outer rack to the center, and placing a fresh rack in the outside position thus vacated; By moving alternate outside rat-rs to the center every 'ack will be uniformly treated. in this step of the process.

Aftei'"washing, in the tank 12, the racks are placed. in the tank i l, the inner surface thereof being a conductor and which tank contains an electrolyte comprisingequal volumes of sulphuric acid of 1.8 1. specific gravity, and pure water, and subjected to anodic direct current, the inner surface of the container being connected as a cathode. This step is for removing oil, organic matter, and graphitic and carbonaceous substances which may remain on the surface. After being subjected to this process the articles are again washed in the tank 12.

The parts are then dipped in the bath 1.7 of hydrochloric acid of about 1.16 specific gravity, and after washing again in the tank 12 are ready for plating.

The rack used in the process is of a construction peculiarly adapted to resist the corrosive action of the electrolytes and processes to which it is exposed, and at the same time conserve the amount of current used. in the step wherein the parts are subjected to anodic direct current in a sulphuric acid electrolyte.

To this end a rack 50 of brass, with copper or iron hooks 54: fastened to the cross bars 52 thereof in a manner to insure good electric cont-act therebetween is employed. The brass reacts with the sulphuric acid, when subjected to anodic direct current therein, to form upon itself a film of oxide which acts as an insulator and prevents an excessive flow of direct current between the rack itself and the container during that step of the process. hen first placed in the. sulphuric acid electrolyte and subjected to anodi-e direct current there is a flow of current for a short period, which then drops markedly, thus den'ionstrating the insulative action above mentioned. The zinc oxide is dissolved when the current removed and the article rack is placed in the bath of h vdrochloric acid.

ll here an iron tank used in the above step it is acted upon to a sv ght degree when not in active use, and to a still less extent when in use, as the tank is connected as a cathode. Corro ive action can be still further reduced by lining the tank with copper, lead, or some other protective conductor.

'lhis process is especially valuable in the reclaiming or otl'ierwise pre mring for refinisliingparts treated in accordance with. the process disclosed and claimed in the Patent- 1, l6'. ,17e granted September at, 1922 to P. E. Kern.

hat is claimed is:

1. A process of removing higher iron oxides from a metal part, which consists in reducing the higher oxide to ferrous oxide, and dissolving the reduced oxide in hydrochloric acid.

2. A process of cleaning a metal part, which consists in subjecting the part of alternating current in a solution of iron chloride and substantial amounts of hydrochloric acid.

8. A process of cleaning a. metal part, which consists in preliminarily subjecting the partto an electric current in a solution containing hydrochloric acid as a constituent and in subjecting said part as an anode to direct current in a solution of equal parts by volume of water and sulphuric acid having a specific gravity of 1.84;.

l. A process of cleaning a metal part, which consists in subjecting it to alternating current in an electrolyte of a solution of ferric chloride and hydrochloric acid to remove scale and rust therefrom, and thereafter as an anode to direct current in a sulphuric acid solution to remove foreign matter.

5. A process of cleaning a metal part, which consists in subjecting it to alternating current in an electrolyte of ferric chloride containing 5% to 10% of hydrochloric acid, specific gravity 1.16, and thereafter as an anode to direct current in a sulphuric acid solution.

6. A process of cleaning a metal part, which consists in subjecting it to alternating current in an electrolyte of a soluble chloride, and thereafter as an anode to directcnrrent in a sulphuric acid solution.

7. A process of cleaning a metal part, which consists in subjecting the part to alternating current in a chloride solution, subjecting it as an anode to direct current in a sulphuric acid electrolyte, and then washing it with hydrochloric acid.

8. A. process of cleaning a metal part, which consists in subjecting it to alternating current in an electrolyte of a soluble chloride, and thereafter as an anode to direct current in a solution of equal parts, by volume, of water and of sulphuric acid, specific gravity 1.84:.

A. process of cleaning a metal. part preparatory to plating, which. consists in suspending the part in a bath of a soluble chloride, subjecting it to altermit-ing current, Washing said part in water, placing it in a bath of equal parts, by volume, of Water and of sulphuric acid, and subjecting it to anodic direct current, Washing: it, placinsr it in a bath of dilute hydrochloric acid, and washing it again.

10. A process of cleaning a metal part, which consists in subjecting itto alternating electrical. current in an iron chloride solution to remove scale therefrom, Washing the part in Water, subjecting it as an anode to direct current in a solution of equal parts, by volume, of Water and of sulphuric acid having' a specific gravity of 1.84, Washing the part in Water, Washing it with a solution of hydrochloric acid, and thereafter washing it in water.

11. A process of cleaning a metal part, which consists in supporting said part on a framework, suspending the framework in an electrolyte, passing electric current from the support and part through the electrolyte to coat the exposed surface of the framework with a non-conductin film. and continuing the passage of the current from the part through the electrolyte.

12. A process of cleaning a metal part preparatory to plating, which consists in suspending the part from a rack, placing it in a bath of a soluble chloride, subjecting it to alternating current therein, Washing it, placing it in a bath of equal parts, by volume, of water and sulphuric acid having a specific gravity of 1.84:, subjecting it to anodic direct current therein, Washing it, placing it in a bath of dilute hydrochloric acid, and Washing again.

13. A process of cleaning, a metal part, which consists in placing it in a bath of ferric chloride containing 10% of hvdrochloric acid, subjecting it to alternating current therein, Washing it in Water, placing it in a bath of equal parts, by volume, of Water and of sulphuric acid having a specific gravity of 1.84 contained in an iron vessel, connecting it as an anode to a direct current while the iron vessel is connected as a cathode, Washing it, placing it in a bath of dilute hydrochloric acid, and Washing again.

14;. A solution for electrolytically cleaning a metal part, comprising iron chloride and substantial amount of hydrochloric acid.

15. A solution for electrolytically cleaning a metal part, comprising an iron chloride solution containing 5% to 10% hydrochloric acid.

In witness whereof, I hereunto subscribe my name this 26th day of May A. 1)., 1923.

SUMNER REDWAY MASON. 

